1. Field of the Invention
This invention relates to a semiconductor device and a method of fabricating the semiconductor device.
More particularly, the present invention relates to a gyro having a semiconductor ring laser and a method of fabricating such a gyro.
2. Related Background Art
Gyros for detecting the angular velocity of a moving object such as mechanical gyros provided with a rotor or an oscillator and optical gyros are known.
Particularly, optical gyros are innovative in the field of gyro technology because they can instantaneously start to operate and have a wide dynamic range. Optical gyros include ring laser type gyros, optical fiber gyros and passive type oscillator gyros. Of these, ring laser type gyros realized by using gas are the earliest corners in the race of technological development and have already found practical applications in the field of aeronautics. In recent years, there have been proposed compact and high precision semiconductor ring laser type optical gyros formed on a semiconductor substrate to achieve an enhanced degree of integration. For example, such optical gyros are described in U.S. Pat. No. 4,431,308 (Japanese Patent Application Laid-Open No. 57-43486) and Japanese Patent Applications Laid-Open Nos. 4-174317 and 5-288556.
Of the above listed patent documents, U.S. Pat. No. 4,431,308 describes a gyro that utilizes the phenomenon that the semiconductor laser element contained in it changes its terminal voltages as a function of revolution and is adapted not to take out any light to the outside from the semiconductor laser element. Referring to FIG. 8 of the accompanying drawings, the semiconductor laser element 100 has electrodes 101 and 102 that are vertically oppositely arranged. Additionally, there are shown a DC blocking capacitor 103, an output terminal 104 and a resistor 105. As shown in FIG. 8, the semiconductor laser element that operates as laser element in a ring laser device is connected to a drive power source 106 and the frequency difference (beat frequency) between the beam circulating clockwise and the beam circulating counterclockwise is detected as the difference in the terminal voltages that is produced when the device shows a certain angular velocity.
However, known semiconductor ring laser type optical gyros have been proposed mainly to prove their functional advantages. Particularly, gyros of the type that utilizes the phenomenon that the semiconductor laser element contained in it changes its terminal voltages as a function of revolution and is adapted not to take out any light to the outside from the semiconductor laser element have never been marketed. In other words, known semiconductor ring laser type optical gyros have not been scrutinized from the viewpoint of assembling particularly in terms of radiation of heat, cost, stability for position control and reliability of the gyro.
Therefore, it is the object of the present invention to provide a semiconductor device having a semiconductor ring laser that excels in heat radiativity, cost, stability for position control and reliability.
According to an aspect of the present invention, there is provided a semiconductor device comprising a semiconductor ring laser wherein the semiconductor ring laser having a circularly formed ridge optical waveguide and a base member having an electrode on a surface thereof are contacted with each other through the intermediary of a conductive member in a concave region of the semiconductor ring laser.
Preferably, in the semiconductor device according to the present invention, the semiconductor ring laser is adapted to generate circularly counterpropagating laser beams respective oscillation frequencies of which beams differ from each other.
Alternatively, in the semiconductor device according to the present invention, the semiconductor ring laser is adapted to generate circularly counterpropagating laser beams respective oscillation frequencies of which beams differ from each other when the device is held stationary.
In another aspect of the present invention, there is provided a method for fabricating a semiconductor device comprising a semiconductor ring laser which comprises the step of contacting a semiconductor ring laser having a circularly formed ridge optical waveguide and a base member having an electrode on a surface thereof with each other through the intermediary of a conductive member in a concave region of the semiconductor ring laser.